Photodynamic Therapy (PDT) is a new technology for the diagnosis and treatment of diseases by using the photodynamic effect. This therapy is based on the photodynamic effect. This is a photosensitization reaction with biological effects in which oxygen molecule is involved. It comprises the following processes: the photosensitizer absorbed by a tissue is excited by the irradiation of a specific wavelength of laser; and then the excited state of the photosensitizer transfers energy to the oxygen in the surrounding environment, to generate a highly active singlet oxygen; singlet oxygen and adjacent biomacromolecules occur oxidation reaction, and thus produce cytotoxicity, which in turn leads to cell damage and even death. Compared with traditional therapies, photodynamic therapy has the advantages of less trauma, good targeting, no drug resistance and side effects. However, since photodynamic therapy mainly uses in the range of more than 600 nm wavelength in the red light region, the light in this region will be lost due to the absorption in a human body. Generally, only the light having the wavelength in few millimeters to several tens of millimeters can be transmitted. For some tumors deep in the body, photodynamic therapy is ineffective. With the aid of optical fiber, endoscopes, and other interventional techniques, the laser can be directed into the deep of body for treatment, avoiding the trauma and pain of surgery such as thoracotomy and laparotomy. Currently, light can be introduced into the body by a puncture needle comprising optical fiber. However, in order to overcome the resistance during puncturing, the optical fiber is wrapped by a hard metal material. Therefore, the needle tubing is thicker. During the process for puncturing, a large pressure is required to perform the puncturing, which is likely to cause a larger trauma and damage to the normal vascular tissue, and bleeding.
Photodynamic therapy produces singlet oxygen to kill tumor cells, in which the fluorescence yield of singlet oxygen is an important indicator of the therapeutic efficacy. Currently, the yield of singlet oxygen is generally determined by analyzing residual fluorescence in the blood, or by analyzing a sample obtained from the puncture, which cannot be able to achieve rapid on-line detection, and has a great impact on the treatment effect and the accuracy of the case studies.